The Chinese military and the CCP are two aspects of the same thing. It may not be the CCP leadership driving the tank, but the tanks are commanded by a CCP party member; it's CCP leadership directing the tanks.
The Chinese military is not a separate military in the way we think of it in the West. They are the armed wing of the Chinese communist party. An enormous amount of time is spent on political indoctrination; not just when joining the PLA, but continuing throughout one's time in the PLA. Senior military commanders are senior party members. The PLA does not stand for the the Chinese constitution or the Chinese people, but for the CCP, of which they are an integral part.
The military is governed by CCP, not the conuntry.
"China's military said on Sunday it must be governed by the ruling Communist Party and not succumb to "liberal" voices who wish to challenge the party's control." [1]
[1] http://www.reuters.com/article/2015/06/07/us-china-defence-i...
Well, I dunno. The Soviet military refused to back the Communist Party in 1991; Churchill wrote that the German military was planning to overthrow Hitler in 1938 in what they thought was the likely scenario of his policies resulting in the UK and France entering into a war with Nazi Germany. So it all depends.
But did the communist party refuse to back the communist party? Because the PLA is part of the CCP. It's not a separate military. It's the armed wing of the Chinese Communist Party. Senior PLA officers are senior party members. The PLA, by design, owes its first loyalty not to the people, or the law, or the constitution, but to the CCP. Significant political education goes on, permanently, to keep it this way.
I'm not saying it's impossible, but it wouldn't be a military coup; it would be the CCP splitting and turning on itself.
